Cell Noise and Anode Rod Current Fluctuation

Jan 24, 2023

There are various causes of cell noise in the production process of aluminum electrolytic cells, so the nature of the noise is also different. According to the waveform and frequency classification of the cell noise signal, the cell noise can be roughly divided into disorder noise (anode noise) and ordered oscillations (electromagnetic force noise) two types. The method of increasing the anode distance to suppress it is often effective for disordered noise, but it is often ineffective for orderly oscillation. There are indications that the electromagnetic force noise is excited by the movement of the anode. Often causes tank instability. The correct way to suppress noise should be to distinguish the nature of the noise, quickly find the noise source, and take targeted suppression measures.



The noise of aluminum electrolytic cell comes from the abnormal fluctuation of molten aluminum (magnetic fluid) and molten electrolyte in the tank. The noise generated in the production process of aluminum electrolytic cells can be roughly divided into two categories due to different causes: one is disordered noise (anode noise); the other is ordered oscillation (electromagnetic noise). The waveform, period, and frequency of disordered noise are disordered. The cause of occurrence is localized and sporadic. The waveform, period and frequency of the ordered oscillation (electromagnetic force noise) are orderly, and the frequency is low frequency (period 40-80s). The causes of formation are global and regular.

Disorder noise, most of this kind of noise is caused by anode process, so it is also called anode noise, because the frequency of this kind of noise is relatively high, it is also called "needle vibration". For the suppression of disordered noise, it is often effective to increase the pole distance. In order to suppress the orderly oscillation, the method of increasing the pole distance is adopted. Sometimes it doesn't work. In addition, the phenomenon of more and more disorder will occur. The suppression of this type of noise requires many measures such as adjustment, improvement of process specifications, and careful operation to be effective.

Anode short-circuit noise: During the production process, due to poor technology and operation, the cathode and anode carbon blocks will fall off and deposit, which shortens the local pole distance or even short-circuits the groove. At this time, the local anode current rises sharply, and the cell voltage (Slot resistance), the waveform of the anode guide rod current also changes accordingly. A distinctive feature of anode short-circuit noise is waveform spikes. Indicates that the electrolyte is broken down suddenly. There are many reasons for the short-circuit of the anode, such as the cracking and falling off of the anode carbon block and the accumulation of precipitates on the cathode surface. In short, this phenomenon only occurs locally and "sporadic." Increasing the pole distance is often effective in suppressing this noise.